Safety switch



Sept. 19, 1944. F w MURPHY 2,358,729

SAFETY SWITCH Filed NOV. l2, 1941 Patented Sept. 19, 1944 vUNITEDl STATES PATENT OFFICE SAFETY SWITCH Frank W. Murphy, Mount Carmel, Ill.

Application November 12, 1941, Serial No. 418,814

(ci. 12s-146.5)

2 Claims.

This invention relates to safety devices for internal combustion engines of the stationary type.

At the present time where an internal combustion engine is mounted on a stationary base for operating a pump or other structure the engine is operated at a predetermined speed and is vfrequently unattended for varying periods of time. It is not infrequent during the operation of the engine that either or both the oil and Water become unduly low or unduly heated with resultant damage to the engine. It is, therefore, an object of this invention to provide a safety means for an engine of this type which Will automatically stop the engine when the oil or oil pressure becomes low or when the water in the cooling system becomes unduly heated.

Another object of this invention is to provide a safety means oftln's type which may be combined with conventional oil and water gauges.

A further object of this invention is to provide a safety device of this kind in combination with a magneto fori-grounding' the magneto and thereby shorting or shunting the ignition circuit for lthe engine so that the engine will stop when the operating conditions are abnormal and before any material damage occurs to the engine.

To the foregoing objects and others which may hereinafter appear, the invention consists of the novel construction, combination and arrangement of parts as will be more specically referred to and illustrated in the accompanying drawing, but it is to be understood that changes, variations and modifications may be resorted to whichV fall within .the scope of the invention as claimed.

In the drawing:

Figure l is a detail front elevation of an instrument panel embodying this invention and showing diagrammatically the electric circuit associated therewith, and

Figure 2 is an .enlarged fragmentary sectional view taken on the line 2-2 of Figure 1.

Referring to the drawing the numeral I designates generally a panel which is adapted to be mounted either on or adjacent an internal combustion engine, and preferably an engine of the stationary type which operates a well pump or other article of machinery. The panel I0 is preferably of metal and is provided with openings I3 by means of which it may be mounted on a suitable support or bracket.

A. gauge member II is mounted in the panel l0 and is of conventional construction, and of the type used for indicating the temperature of the water in the water cooling system associated with the internal combustion engine. A second gauge member I2 is mounted in the panel I!! adjacent the gauge II, and vis a conventional gauge of the type used for indicating the oil pressures 0r oil ow through the lubricating system of the engine. The operating or internal mechanisms of the two gauges II and I2 are well known, and

their connections with the engine are conventional and well known. It is thought unnecessary to show specifically the connections from the gauges Il and I2 to the particular parts of the engine.

The gauge II includes a swinging hand or indicator I4 which is mounted on a rock shaft I5, and the hand or pointer I4 is disposed on the forward side of a graduated dial I6. The dial I6 includes a space Il having the legend Cold imprinted thereon, a second space I9 having the legend Run imprinted thereon and indicated at 20. The dial IB also has a third space 2l having the legend Hot therein and designated by the numeral 22. During the normal running of the engine the pointer I4 will be disposed within the space or area I9 and confronting the legend. 20. With stationary engines of the type used in operating pumps or other articles of machinery it is not infrequent that the engine is left unattended and in running condition for a considerable period of time, and during this unattended period the engine is liable to become overheated with consequent increase of the temperature of the water in the cooling 'system and reduction in the quantity of water to the point where damage will occur to the engine by reason of the overheated condition.

In order to provide a means whereby the engine will be automatically cut oi from the ignition system when the water becomes unduly heated and before any damage may occur, I have provided an electric circuit which is connected with the magneto operated by the engine so that the ignition circuit will be shorted or grounded, and the engine thereby stopped before any damage may occur. A magneto 23 is operated by the internal combustion engine in the usual manner and has one side thereof grounded as by a conductor 24.

The other side of the magneto 23 is connected by means of a conductor 25 to the ignition circuit of the engine, and under normal conditions, the electric current will flow from the magneto 23 through the conductor 25 to the distributor and from the distributor to the spark plugs of the engine and from the spark plugs to the ground, and then from the ground back through the conductor 24 to the opposite side of the magneto 23.

In order to provide a means whereby the electric circuit including the conductors 24 and 25 and the magneto 23 may be grounded in order to stop operation of the engine when the operating conditions are abnormal such as the overheating of the fluid in the cooling system, I have provided an adjustable contact member 2G which is positioned interiorly of the water gauge II.

The contact member 26 is of elongated construction and shown in greater detail in Figure 2. This contact member 26 is positioned in the path of the swinging movement of the pointer 24, so that when the pointer 24 engages the inner end of the contact member 26, an electric circuit will be completed from the contact member 26 through the pointer I4 to the ground. A threaded stem or shaft 21 is formed integral with and is coaxial with the contact member 26. The stem or shaft 21 is threaded through a cylindrical insulating sleeve 28 provided with a threaded bore 29. The sleeve 28 extends through a threaded opening 30 which is formed in the wall 3l of the gauge I I.' The nut 28 provides a means for insulating the stem 21 and the contact 26 from the metallic wall 3I.

A holding nut 32 is threaded on the stem or shank 21 and bearsagainst the outer end of the sleeve .28 so that tightening of the nut 32 on the stem or shank 21 will hold the stem or shank 21 tightly with respect to the sleeve 28. A lock nut 33 is also threaded on the stem or shank 21,

and a washer 34 is interposed between the lock nutl 33 and the holding nut 32.

An extension 35 is formed integral with the washer 34, and one end of a conductor 31 is adapted to be connected to the extension 35, and the other end of the conductor 31 is connected to a conductor 38. The conductor 38 at one end is connected to a switch contact member 39. A switch blade 40 of conventional construction is pivotally mounted on a'pivot 4I and is adapted to engage, when in circuit closing position, with the contact 39. A conductor 42 is connected at one end to the pivotv 4I`and at the other end is connected to the conductor 25.

The oil gauge I2 is provided with a dial 43 having graduations 44 thereon, and a swinging pointer 45 is carried by a rock shaft 48 associated with the internal mechanism of the gauge I2 and adapted to rock in order to swing the pointer 45 for indicating -the pressure or quantity of oil in the lubricating system. The pointer 45 constitutes one side of a switch structure, the other side of which is formed by an assembly generally designated as 41 which is similar in every detail to the assembly shown in Figure 2. A conductor 48 is connected at one end with the switch assembly 41, and the opposite end of the conductor 48 is connected to the common conductor 38. VThe panel III is formed with an elongated slot or opening 49 within which the assembly associated with the gaugeV II loosely engages, and the panel I0 is also formed with a second slot or elongated opening 50 within which the switch assembly 41 engages. The panel I0 may be grounded directly to the engine by the bolts engaging throughthe openings I3 and I3a o-r may be grounded by means of a conductor 5I which is connected at one end with the metal panel I0 and at the opposite end with the ground.

In the use and operation of this safety assembly the switch structure embodying the contact 26 is mounted through the wall 3I of the gauge I I, and the assembly 41 is mounted through the wall of the casing for the gauge I2 and is electrically insulated therefrom. During the normal operation of the engine the pointer I4 of the water gauge II will be disposed within the space I9 on the dial I6. Y Y

The pointer I4 is actuated by the conventional thermostatic means and when the temperaturer of the water in the cooling system becomes unduly heated, the pointer I4 will swing to the right as viewed in Figure 1 and will engage the inner end of the contact 2li.y When the pointer I4 engages the contact 26, and with the switch member 40 engaged in the contact 39, a grounding circuit will bc completed from the conductor 25 through the conductor 42, switch arm 40, contact 39, conductor 38, conductor 31, contact` 26, and pointer I4 to the ground. The closing of this grounding circuit will short the ignition circuit from the magneto 20 to the engine and thereby stop operation of the engine.

In the event the quantity or pressure of the oil in the lubricating system should drop below a pre-determined degree before the water becomes unduly heated and the engine is stopped by the safety switch structure associated with the water gauge II, the pointer 45 of the oil gauge I2 will swing to the left and engage the contact 52 forming part of the switch assembly 41. The engagement oi' the pointer 45 with the contact 52 and with the switch blade 40 in engagement with the contact39 will close a circuit from the magneto 23 through conductor 25, conductor 42, switch blade 40, contact 39, conductor 38, conductor 48, contact 52, and pointer 45, to the ground thereby shorting the ignition circuit and eilecting stoppage of the engine. f

The provision of the adjustable contacts 26 and 52 provides a means whereby the snorting or grounding circuit connected with the magneto 23 may be closed at any pre-determined point, and preferably at a point in the operation of the engine where damage has not yet occurred to the engine by reason of the heated condition of the cooling system or the failure of reduction in the quantity of oil in the lubricating system. The safety means hereinbefore described may be combined with conventional water and oil gauges without changing the present construction of the gauges, it only being necessary to form an opening in each gauge within which the insulated switch assembly may be mounted, and the switch assemblies then connected with a. grounding circuit provided with a manually operable switch.

What I claim is:

1. In an internal combustion engine having an ignition circuit, a magneto and a liquid indicator gauge, said gauge including a metallic casing grounded to said circuit, and a movable metallic pointer; said casing having an opening in a wall thereof adjacent said pointer, an insulated internally and externally threaded sleeve threaded through said opening, an adjustable contact, a threaded shank integral with said contact and threaded through said rst sleeve, a holding nut on said shank bearing against the outer end of said sleeve, a connector carried by said shank,

and means connecting. said connector with saidV ignition circuit whereby engagement of said pointer will ground said ignition circuit.

2. In an internal combustion engine having an ignition circuit, a magneto in said circuit and a liquid indicator gauge, said gauge including a metallic casing grounded to said circuit, and a movable metallic pointer also in said circuit; said casing having an opening, an insulated sleeve in said opening, an adjustable contact within said casing and adapted to be engaged with said pointer at a predetermined position of the latter, a threaded shank xed to said adjustable contact and threaded through said sleeve, and means connecting. said shank with said circuit whereby engagement of. said pointer with said contact will ground said circuit at a predetermined position of said pointer.

FRANK W.V MURPHY. 

